backfiring!!!!!!!

it looks like im gonna have to split it.even when i do split it and put it back together ill probably have the same problem but its lookin like thats what iv gotta do...thanks for all the help everyone ......any more suggestions?
 
right......i took out the manston and put in an almost new(only about 40 or 50 miles on the clock) MHR cylinder that i usually have on my other gilera and while the MHR seemed to be working better on the crankcase than the manston i went for a quick drive....my manston setup was working very good on the MHR but while i was driving down the road at about 13/14k the bearings went!!!!!!nnnnnnnnnooooooo!!!!!!!!!!anyway....now both my bikes are off the road now and im real pissed off with them both....new race bearings and seals on the way for the manston bike as i recon it was a problem with the seals all along
 
deanjdk said:
right......i took out the manston and put in an almost new(only about 40 or 50 miles on the clock) MHR cylinder that i usually have on my other gilera and while the MHR seemed to be working better on the crankcase than the manston i went for a quick drive....my manston setup was working very good on the MHR but while i was driving down the road at about 13/14k the bearings went!!!!!!nnnnnnnnnooooooo!!!!!!!!!!anyway....now both my bikes are off the road now and im real pissed off with them both....new race bearings and seals on the way for the manston bike as i recon it was a problem with the seals all along

Oh, this is a very bad news! :( I hope you can fix your problem very soon!

What type of bearings did you have? What type of basket have they got ( nylon or a metal)?
 
yea browni this is very bad news!lol....anyway...im just waiting for the new bearings to come and it should all be sorted as ill strip the engine down all the way and rebuild it from the ground up making sure everything is clean and in good condition as nothing like this goes wrong again!by the way....what brand of sealant would you recommend for sealing back up the crankcase(carter)as the sealant i usually use might have caused the problem(maybe a piece of excess sealant could have came loose inside the carter and got caught in the bearings of something).also for a manston would you recommend adjusting the spark advance.thanks for your help everybody
 
"What type of bearings did you have? What type of basket have they got ( nylon or a metal)?"

waht i think you mean is what type of seals i use......i use nylon...the bearings i was using were C4 race bearings from scootercenter but i might have hit them too hard when i was installing them and thats why one of them destroyed itself i recon
 
The best sealant for the carters for me is the Locktite of blue colour. Never use the red one. For an simply reason; the red one becomes elastic, while the blue one becomes much more plastic. Also you should apply a very fine layer of sealant on the sealing areas.

For an LC engine C4 bearings are not needed. We use normal SKF (they are C2) on racing ZIPs. They have nylon chage. You should never hit anything when mounting the crankcase together. Well except a few axial hits to set the axial play after the crankcase is together.
 
deanjdk said:
"What type of bearings did you have? What type of basket have they got ( nylon or a metal)?"

waht i think you mean is what type of seals i use......i use nylon...the bearings i was using were C4 race bearings from scootercenter but i might have hit them too hard when i was installing them and thats why one of them destroyed itself i recon

No, I meant the bearing's cage. And as roost said I don't think the C4 is necessary for your bike. I use the NTN C3 bearings with riveted metal cage, and it is very massive! You can use blue Loctite or I know another brand, it has got a very good black sealant, but I don't know it's name!
 
roost said:
The best sealant for the carters for me is the Locktite of blue colour. Never use the red one. For an simply reason; the red one becomes elastic, while the blue one becomes much more plastic. Also you should apply a very fine layer of sealant on the sealing areas.

For an LC engine C4 bearings are not needed. We use normal SKF (they are C2) on racing ZIPs. They have nylon chage. You should never hit anything when mounting the crankcase together. Well except a few axial hits to set the axial play after the crankcase is together.

I think you meant pulling not hitting:)
 
i never hit anything when putting the crankcase together except the bearings but i use a mallet for that (either leather or rubber).i think its the blue loctite that i use(cant remember exactly but ill buy another fresh tube anyway....what about spark advance ....will i leave it the same for the manston?
 
Browni: pulling??:)
No, I meant hitting. When I fasten the bolts that hold the crankcase together, the movement of the crankshaft becomes a little harder. So with an few hits with an piece of aluminium in the axial direction on the side of the vario and the ignition, the axial tension on the bearings is relieved.
This is an very important procedure, because if it is not done and if the bearings don't slid by themselves into the proper position, they will overheat and fail.
 
roost said:
Browni: pulling??:)
No, I meant hitting. When I fasten the bolts that hold the crankcase together, the movement of the crankshaft becomes a little harder. So with an few hits with an piece of aluminium in the axial direction on the side of the vario and the ignition, the axial tension on the bearings is relieved.
This is an very important procedure, because if it is not done and if the bearings don't slid by themselves into the proper position, they will overheat and fail.

I naturally know it!

But you do it very wrong, never hit the cranksahft when you adjust the axial play, you have to pull it with a tool (I use a custom made for my Minarelli engine)! I think you made a lot of damaged bearings:)
 
roost said:
Browni: pulling??:)
No, I meant hitting. When I fasten the bolts that hold the crankcase together, the movement of the crankshaft becomes a little harder. So with an few hits with an piece of aluminium in the axial direction on the side of the vario and the ignition, the axial tension on the bearings is relieved.
This is an very important procedure, because if it is not done and if the bearings don't slid by themselves into the proper position, they will overheat and fail.

"When I fasten the bolts that hold the crankcase together, the movement of the crankshaft becomes a little harder."

That's a typical wrong assembly:) So you pull the crankshaft/bearings to their place with the engine screws? :?
 
deanjdk said:
i never hit anything when putting the crankcase together except the bearings but i use a mallet for that (either leather or rubber).i think its the blue loctite that i use(cant remember exactly but ill buy another fresh tube anyway....what about spark advance ....will i leave it the same for the manston?

Hm the Manston has a very high compression, so the standard advance maybe too much for high revolutions, but I can't recommend you an exact value, maybe a 13-12 degree?? Or buy a variable advance!
 
Browni said:
"When I fasten the bolts that hold the crankcase together, the movement of the crankshaft becomes a little harder."

That's a typical wrong assembly:) So you pull the crankshaft/bearings to their place with the engine screws? :?

I think we are talking about different things.
I first insert the bearings on the crankshaft. Then insert the crank into the case. I use a heat pistol, with heat I make absolutely no hits to any part of the setup, neither I use no force to insert any part into the other. No way I would pull the block together with the bolts!!!
But when you strenghten the bolts, because of the sealant layer and thermical shrinking makes a little axial pressure to the bearings. So then I heat up again the whole block and with a few axial hits (in reality are more a ticks) on the sides relieves this pressure.
It's for the axial play that the bearings have to have and it's about less than 0,1mm.

I don't like the procedure of pulling the crank into the bearings.

And I never ever had a bearing failure, and I had lots of lower end rebuilds.
 
roost said:
I think we are talking about different things.
I first insert the bearings on the crankshaft. Then insert the crank into the case. I use a heat pistol, with heat I make absolutely no hits to any part of the setup, neither I use no force to insert any part into the other. No way I would pull the block together with the bolts!!!
But when you strenghten the bolts, because of the sealant layer and thermical shrinking makes a little axial pressure to the bearings. So then I heat up again the whole block and with a few axial hits (in reality are more a ticks) on the sides relieves this pressure.
It's for the axial play that the bearings have to have and it's about less than 0,1mm.

I don't like the procedure of pulling the crank into the bearings.

And I never ever had a bearing failure, and I had lots of lower end rebuilds.

No, we talk about the same thing! :)

You can preload the crankshaft a little, with a pulling tool (from the side where you put the cranksfat first), so when you reassembly the other half of the crankcase you can rotate the crankshaft very easily, after you tighten the crankcasebolts!

However in a Piaggio engine, the axial play must be:

0,10-0,12 if it is hot

and 0,06-0,08 mm when it's cold

But, if you have 0,02-0,03 mm then you have to reassembly the crank again, and never hit it!
 
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